Teeth are an important organ indispensable for the mastication of food and the utterance of speech sounds. In order for the teeth to perform their functions, it is necessary for them to be brushed after meals or before sleeping to prevent tartar and calculus from being deposited on dental necks for protection against periodontites.
For brushing teeth, it has heretofore been customary to use tooth brushes having bristle assemblies planted on an end of a handle. Electric toothbrushes that have been developed in recent years have also been widely used.
Toothbrushes and electric toothbrushes, which are respectively manually and automatically operable, are generally used by turning the bristle assemblies back and forth about the toothbrush axis.
However, the conventional toothbrushes and electric toothbrushes have suffered the following drawbacks:
When the handle of a toothbrush is rocked about its own axis in use, the bristle assemblies are angularly moved alternately upwardly and downwardly. More specifically, when the user of an electric toothbrush holds its grip cylinder and angularly moves the bristle assemblies about the axis while keeping the bristle assemblies against a tooth side or neck, a downward swinging movement of the bristle assemblies peels an end of the gum off the tooth neck, and pushes a deposit of plaque into a recess that is formed between the peeled gum and the tooth neck. Therefore, the brushing operation tends to produce a deposit of tartar and calculus, causing periodontites such as a dentoalveolitis.